Control systems and monitoring systems are of the real-time system type. In such systems, it is important to be able to relate different detected events to each other in time. In centralized systems, it is simple to fulfil the requirement by relating to a central clock. In distributed systems, the problem is greater as the physical connection to a common clock requires either special clock communications links and hardware or for local clocks to be used. For the alternative with local clocks, two solutions are described that can be regarded as the background art:    1. synchronizing of local clocks to a master clock.            SE 466 123 describes how local clocks can be synchronized to a selected reference clock with utilization of signals on a common bus link.            2. Conversion of local times.            EP 0570 557 describes how local clocks can convert their local time to that of another and vice versa, with utilization of signals on a common bus link.        
Both the solutions require the modules to be connected to a common communications link and also require the modules to have a common protocol for time messages. This limits the choice of modules for a system architect. Many systems consist of subsystems that are connected together via gateways. This leads to a problem for the system designer when subsystems are to work together in real time, as the subsystems are not interconnected to a common communications link. A special category of monitoring system comprises analysis tools. The actual analysis software is usually executed under an operating system that does not have real-time characteristics, for example Windows or Linux. It is common in industry for the analysis to cover several subsystems that work together. Within the automobile industry, CAN and LIN systems and CAN High Speed and CAN Low Speed are commonly used. Each system is analysed via one or more connections to respective subsystems via hardware configured for the analysis tool that comprises a common clock function for time-stamping. The product “Sync Box XL” from Vector Informatik GmbH is an example of the background art. Here there is a special synchronizing lead for generating synchronization pulses. Upon the reception of a high-to-low edge on this lead, each connected unit time-stamps this event. This solution requires a special hardware arrangement and, in addition, it must also be ensured that electromagnetic interference does not give false time indications. There is thus a need to enable different modules to work together at system level within given time frames without a common protocol for time synchronization and a need to be able to time-relate information from one module to information from other modules without special hardware or communications links for processing in a computer without a real-time operating system. The proposed solution solves both problems.
There is also a need to be able to eliminate arrangements for synchronizing local clocks to other clocks, that is a need for a device to eliminate the requirement for synchronization of a clock in one module to a clock in another module. In addition, there is a desire for increased configurability and more ways of relating times and events. Communications links must be able to be utilized together with reference events and different clocks. In addition, there is a desire for increased freedom of action and to be able to achieve different solutions to the problem in question. Global time must be able to be utilized, and also stand-alone clocks. It should also be noted that during adjustment of clocks, the system function can not be utilized.